1. Field of the Invention
The present invention relates to an electric wire testing apparatus for testing the condition of an end portion of an electric wire that includes a plurality of core wires and a sheath for covering the core wires. The present invention also relates to an electric wire processor equipped with the testing apparatus.
2. Description of the Related Art
As a conventional example of this type of testing apparatus, the testing apparatus disclosed in JP 05-079824A has been known. This testing apparatus has a lighting means for illuminating an end of the core wires from which the sheath has been stripped off, an imaging means disposed facing the lighting means, for photographing the end portion of the core wires from the side, and an image processing means for processing an image photographed by the imaging means, and a monitor for displaying an image processed by the image processing means. This testing apparatus tests the condition of an end portion of an electric wire based on, for example, the coordinate positions of the sheath and the core wires and the inclinations of the core wires, which are obtained from the brightness data of the photographed image.
However, the testing apparatus uses only the images of the core wires photographed from one side. Therefore, a problem with this testing apparatus is that if the other side of the core wires has a defect, the defect cannot be detected. For example, if some of the core wires are damaged and lost or some of the core wires are untied in the side that is not photographed, the testing apparatus cannot detect such defects.
JP 2004-156910A discloses an apparatus that photographs the end faces of the core wires with an imaging means and tests the end portion of the core wires for pass/fail based on the total sum of the areas of the end faces in the photographed image.
However, the apparatus that tests a wire end for pass/fail based on the total sum of the areas of the end faces of the core wires may falsely determine a defective product as a non-detective product although some of the core wires are missing, when the total sum of the areas may happen to satisfy a predetermined condition.
Moreover, it is not always easy to measure the areas of the end faces of the core wires accurately. For example, when the sheath of the electric wire which is stripped off is relatively long, the end faces of the core wires that are adjacent to each other have a wide gap therebetween. However, when the gap between the end faces of the core wires is wide, it becomes difficult to measure the areas of the end faces of the core wires accurately. Thus, the apparatus that tests a wire end for pass/fail based on the total sum of the areas of the end faces of the core wires has the problem of low test accuracy for an electric wire having core wires that tend to be untied easily.